The duodenum is the first section of the small intestine[2] in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear, and the terms anterior intestine or proximal intestine may be used instead of duodenum.[3] In mammals the duodenum may be the principal site for iron absorption.[4] The duodenum precedes the jejunum and ileum and is the shortest part of the small intestine.

Image of the gastrointestinal tract, with the duodenum highlighted.
Diagram of the human duodenum with major parts labelled
Pronunciation/ˌdəˈdnəm, duˈɒdɪ-/
PrecursorForegut (1st and 2nd parts), Midgut (3rd and 4th part)
Part ofSmall intestine
SystemDigestive system
ArteryInferior pancreaticoduodenal artery, Superior pancreaticoduodenal artery
VeinPancreaticoduodenal veins
Nerveceliac ganglia, vagus[1]
LatinIntestinum duodenum
Anatomical terminology

In humans, the duodenum is a hollow jointed tube about 25–38 cm (10–15 inches) long connecting the stomach to the middle part of the small intestine.[5][6] It begins with the duodenal bulb and ends at the suspensory muscle of duodenum.[7] Duodenum can be divided into four parts: the first (superior), the second (descending), the third (horizontal) and the fourth (ascending) parts.[6]

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This article uses material from the Wikipedia article Duodenum, and is written by contributors. Text is available under a CC BY-SA 4.0 International License; additional terms may apply. Images, videos and audio are available under their respective licenses.